Two NASA spacecraft, flying millions of miles away from home, have sent back portraits of Earth.

For everyone who ran outside to wave and smile for the camera last Thursday, well, you didn't quite make it into the picture, unless you can spy yourself in what looks like a bright spot in the dark heavens.

Late Monday, NASA released images of Earth and the moon taken from both its Cassini spacecraft, which is about 900 million miles away from Earth studying the Saturn system, as well as from Messenger, which is about 61 million miles away studying Mercury.

"We can't see individual continents or people in this portrait of Earth, but this pale blue dot is a succinct summary of who we were on July 19," said Linda Spilker, NASA's Cassini project scientist. "Cassini's picture reminds us how tiny our home planet is in the vastness of space, and also testifies to the ingenuity of the citizens of this tiny planet to send a robotic spacecraft so far away from home to study Saturn and take a look-back photo of Earth."

In the images that Cassini sent back, Earth and the moon look like nothing more than dots - Earth a pale blue and the moon white - that show up between Saturn's rings. The photos mark the first time Cassini's high-resolution camera captured Earth and its moon as two distinct objects.

For last week's photo shoot from space, NASA encouraged people to run outside and wave toward Saturn while the portrait was being taken.

NASA reported that more than 20,000 people uploaded photos on sites like Facebook and Twitter, commemorating their interplanetary "Say, cheese!" moment.

"It thrills me to no end that people all over the world took a break from their normal activities to go outside and celebrate the interplanetary salute between robot and maker that these images represent," said Carolyn Porco, Cassini imaging team lead, in a statement. "The whole event underscores for me our 'coming of age' as planetary explorers."

NASA noted that it's difficult for a spacecraft to capture a good image, or any image, of Earth from a great distance because of its proximity to the sun. As with human eyes, a spacecraft's cameras can be damaged by focusing on the sun.

However, last Friday was unique because, from Cassini's vantage point, the sun had moved behind Saturn, giving the robotic spacecraft a great view of the Earth.

The Earth's portrait is part of Cassini's work on a mosaic, or multi-image portrait, of the Saturn system. The images are taken to highlight the planet's ring particles and are expected to help scientists discover patterns in Saturn's dusty rings.

Cassini took a similar photo of Earth on June 19. All the images will be added to the mosaic, which isn't expected to be completed for several weeks.

For Messenger's part, the spacecraft took a long-exposure photo of Earth and the moon to capture as much light, and the best image, as possible.

"That images of our planet have been acquired on a single day from two distant solar system outposts reminds us of this nation's stunning technical accomplishments in planetary exploration," said Messenger principal investigator Sean Solomon. "And because Mercury and Saturn are such different outcomes of planetary formation and evolution, these two images also highlight what is special about Earth. There's no place like home."